[PATCH bpf-next v1 03/10] bpf: remove redundant REG_LIVE_READ check in stacksafe()

[Eduard Zingerman <eddyz87@gmail.com>]

stacksafe() is called in exact == NOT_EXACT mode only for states that
had been porcessed by clean_verifier_states(). The latter replaces
dead stack spills with a series of STACK_INVALID masks. Such masks are
already handled by stacksafe().

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
 kernel/bpf/verifier.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 698e6a24d2a2..8673b955a6cd 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -18756,13 +18756,6 @@ static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old,
 		     cur->stack[spi].slot_type[i % BPF_REG_SIZE]))
 			return false;
 
-		if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ)
-		    && exact == NOT_EXACT) {
-			i += BPF_REG_SIZE - 1;
-			/* explored state didn't use this */
-			continue;
-		}
-
 		if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID)
 			continue;
 
-- 
2.47.3